外周激肽B1受体在慢性炎性搔痒中的作用及分子机制研究

Itch induced by algogen in lesional skin of atopic dermatitis. We found that bradykinin evoked itch in complete Freund's adjuvant (CFA)-inflamed skin through activation of kinin B1 receptor (B1R), suggesting a close correlation between B1R and chronic inflammatory itch. B1R located in keratinocytes and nerve fibers will be increased in response to inflammation. Assuming secretion of nerve growth factor (NGF) and production of nitric oxide (NO) through inducible nitric oxide synthase (iNOS) pathway by keratinocytes increased upon activation of B1R, which facilitates the sprouting and proliferation of pruriceptors in inflamed skin. Spontaneous itch will be evoked by bradykinin or its analogues activating the B1R located in pruriceptors. The role of B1R in the chronic inflammatory itch is investigated using the antagonists and B1R gene knockout mice. To explore the mechanisms, the combination of behavior observation, cell culture, immunochemistry stain, RT-PCR and western blotting are planned to evaluate the participation of nuclear factor κB, NGF and iNOS in the process. The current project will clarify the molecular mechanism of chronic inflammatory itch. It will open a new window for the treatment of atopic dermatitis.

特应性皮炎皮损区内注射致痛剂引起搔痒，我们发现在完全佛氏佐剂（CFA）致炎皮损内注射缓激肽通过激肽B1受体（B1R）引起搔痒，提示B1R可能与慢性炎性搔痒有关。炎性反应使角质形成细胞与神经纤维B1R表达增加，我们提出假设认为角质形成细胞B1R激活后促使神经生长因子（NGF）分泌增加并通过诱导型一氧化氮合酶（iNOS）途径增加一氧化氮（NO）的产量，NGF及NO促使皮肤内搔痒感受性神经纤维增生。由于局部组织内存在缓激肽及类似物，激活搔痒感受性神经纤维上的B1R可以引起自发性搔痒。我们计划应用B1R拮抗剂及B1R基因敲除小鼠研究B1R在慢性搔痒中的作用，通过动物行为学、细胞培养、免疫染色、ELISA和Western blotting等技术研究NF-KB、NGF、iNOS在其中的作用从而探讨B1R的作用机制。通过本课题的研究将阐明慢性炎性搔痒的分子机制，并可能为特应性皮炎的治疗研究开拓新思路。

特应性皮炎皮损区内注射致痛剂引起搔痒，我们发现在完全佛氏佐剂（CFA）致炎皮损内注射缓激肽通过激肽B1受体（B1R）引起搔痒，提示B1R可能与慢性炎性搔痒有关。应用二苯基环丙烯酮局部涂沫制成慢性搔痒模型，B1R拮抗剂、NGF抗体及NOS抑制剂可抑制DCP模型动物的自发性搔痒，局部应用B1R拮抗剂可减少局部皮肤NGF含量。机械刺激CFA致炎皮损区可诱发搔抓反应（触诱发痒），B1R拮抗剂可抑制触诱发痒，皮损区注射B1R激动剂可引起搔痒，应用ERK通路抑制剂、MMP-9（Matrix metalloproteinases 9）抑制剂及ASIC3（Acid-sensing ion channels 3）抑制剂可以抑制皮损区注射B1R激动剂引起和搔痒。我们的结果表明B1R在慢性搔痒中起重要作用，为治疗研究开拓新思路。